Ian Marber recently contributed an article to Mail on Sunday: The Food Doctor: How to beat the bloat. Like the curate’s egg, it is good in parts but clearly shows the long-term after-effects of taking one’s education at the Institute for Optimum Nutrition. It was good to see an IONista acknowledge that the blood tests that measure IgG levels to diagnose food intolerance have little utility. However, with a heavy heart, it was with a degree of incredulity that we read Marber’s explanation for bloating – yeast. Yes, although Marber disdains the relevance of IgG food intolerance tests, it looks like he is still promoting yeast as a villain. Yeast, the stalwart income-earner of nutritionists everywhere: the bloat by any other name that smells so foul.

The essential difficulty with Marber’s article, The Food Doctor: How to beat the bloat, is that he is commenting on a phenomenon that is reported by “millions of people” and he goes on to attribute the cause to rampant yeast problems after some sensible comments about the implausibilities of food intolerance, allergies, and the IgG blood test that is promoted by so many of his fellow nutritionists (we apologise to Marber if this is the Mail‘s interpretation of his work).

One of the most common problems that I see at my nutrition clinic causes daily discomfort and misery to millions of people in the UK. It is bloating – defined as a general swelling or feeling of tightness in the abdominal area and often described by clients as feeling ‘very full’ after eating, even after only small amounts…

Countless clients who experience bloating and other symptoms believe they may have some kind of food intolerance – a catch-all term to describe an adverse reaction to a certain food when eaten.

This is entirely different from a food allergy, a medical condition affecting three out of 100 adults, in which the immune system reacts immediately and aggressively to a substance – for example, nuts, or shellfish – causing the body to go into a form of shock.

These clients often come to their appointments clutching test results that show they are intolerant to a host of foods, usually dairy, yeast and wheat.

While some of these cases are no doubt genuine, my own clinical experience of treating bloating has led me to doubt the science behind many of these so-called ‘intolerance tests’.

They almost always rely on testing for the presence of immune cells called immunoglobulin G (IgG).

HolfordWatch is a little conflicted. We are happy to welcome Ian Marber to the party of those who “doubt the science behind many of these so-called ‘intolerance tests'”. We are even happier that he asked Catherine Collins RD for her opinion and she gave a fine synopsis of the current state of the science alongside the best practice.

‘Every time we eat a new type of food our immune system produces IgG antibodies that mark the substance as nonharmful and not a danger.

‘The presence of IgGs in the blood for certain foods isn’t an indicator of intolerance…

‘The best way to find out if you have a food intolerance is to analyse the diet through a detailed food diary.’

However, HolfordWatch would have liked Marber to have arrived at his conclusion about IgG tests from the lack of appropriately-scrutinised clinical evidence to support such a role, or the lack of a demonstrable mechanism of action to justify them, as well as the advice from Collins. Relying upon his “own clinical experience of treating bloating” is not readily verifiable and is open to confirmation bias. Our objection might seem a little unreasonable but Marber had followed that process, then it is (perhaps) less likely that he would still think it appropriate to offer an exclusion diet for dealing with bloat that does not seem to have a strong evidence base in reliable, peer-reviewed literature.

Unfortunately, it is after Marber’s fairly sensible section about IgG food intolerance tests that the article takes a slightly odd turn. There is a claim that:

Countless studies have shown that beneficial bacteria and yeasts that live in our gut and aid digestion have a huge role to play in bloating. And 90 per cent of the cases I see can be easily remedied by making a few simple, short-term dietary changes – which indicates that clients are not, in fact, intolerant to foods.

I have my doubts about the first claim, and the second set of claims would be extraordinary evidence of the sort that it is unfortunate that Marber has not written up and published in a peer-reviewed journal. Bloating and gas are proving resistant to many of the interventions in the current literature and many clinicians would welcome a good series of case-studies or some well-conducted assessments.

Changes in fecal microbiota, the use of probiotics, the phenomenon of postinfectious IBS, and the recognition of an upregulated host immune system response suggest that an interaction between the host and GI microbiota may be important in the pathogenesis of IBS.

However, it does not necessarily follow that something that may be implicated in IBS is necessarily relevant to bloating and gas (which is what Marber seems to be describing). Although bloating[a] and gas may be symptoms of IBS, it doesn’t follow that they are sufficient for a diagnosis of IBS, or that interventions that are appropriate for IBS would be appropriate for bloat and gas.[b] (NB, there is no substitute for an adequate clinical history and discussion with appropriately-qualified medical personnel.)

However, it is logical to expect that qualitative differences in colonic flora might lead to the comparatively disproportionate activity of those species that yield more gas and short chain fatty acids as well as increasing the deconjugation of bile acids.[c] So, it seems plausible that manipulating the colon flora with prebiotics might create a less disruptive ecology. However, there have also been some mixed successes with treating what seem to be changes in bacteria or flora with antibiotics.[d]

Quigley[2] discusses the relative success of some recent studies that assessed the impact of proprietary brands of probiotics and concludes:

These studies with this particular B. infantis strain provide therefore evidence for a benefit in IBS for a clearly defined single-organism probiotics preparation and thereby suggest that some strains may be more effective that others for this indication…
[S]hort-term therapy with either antibiotics or probiotics does seem to reduce symptoms among IBS patients. It seems most likely that the benefits of antibiotic therapy are mediated through subtle and, perhaps, localized, quantitative and/or qualitative changes in the colonic flora; how probiotics exert their effects remain to be defined but an antiinflammatory effect seems likely. While this approach to the management of IBS is in its infancy, it is evident that manipulation of the flora, whether through the administration of antibiotics or probiotics, deserves further attention in IBS.

Some recent randomized controlled studies attest to the efficacy of some probiotics in alleviating individual IBS symptoms while selected strains have a more global impact. Evidence for long-term efficacy is also beginning to emerge though more studies are needed in this regard. Several other issues complicate the interpretation of much of the literature in this area: lack of quality control, use of many different species, and, strains and, above all, significant deficiencies in trial methodology.

There is no indication in the clinical literature that probiotics should only be used in conjunction with the sort of restricted diet that Marber advocates. A fundamental problem with Marber’s diet recommendation is the implication that somehow, it is only the less desirable abundance of particular bacteria and yeast in the colon that will thin their population in response to a diet with a reduced sugar intake. Following Marber’s logic, where will the helpful probiotics obtain the sugar to ensure their sustenance and appropriate territorial expansion? Unless Marber is making recommendations for diabetics who may have increased glucose in their bodily fluids/secretions, there is little obvious justification for the ban on sugar. Unfortunately, the sugar restriction in tandem with the warnings against dietary yeasts sounds like the spectacularly unevidenced recommendations for Candida Albicans. Marber advises against saccharomyces cerevisiae although it is different to candida albicans: this last is typically, yet erroneously cast as a gastrointestinal or even systemic villain although such a diagnosis tends to be made in those who undeveloped or compromised immune systems who have been unable to check the growth. (More about chronic candidiasis at Dr Fungus.[e])

Similarly, although there are some vague assessments in the clinical literature of the role of allicin as a microbial, the evidence is not sufficiently robust for any recommendations for its use as a dietary intervention, far less particular formulations or dosages. Nonetheless, Marber advises:

I suggest taking odourless garlic capsules as the allicin in garlic can work against unwanted bacteria and yeasts in the gut. Take one 200mg capsule three times a day.

Even if garlic capsules could achieve this, why does Marber seem to think that there are garlic supplements with Smart Targeting systems that allow them target only unwanted bacteria and yeast rather than including some of the desirable ones in their general zest to cleanse?

Given his recommendations, it might have been helpful if Marber had provided further guidance as to what readers should do if they followed his plan and developed bloating or a return of symptoms after the re-introduction of particular foodstuffs. There needed to be some better navigation advice on keeping a food diary to keep track of the re-introduced foods and recommendations for actions if this plan failed.

Overall, it would have been very helpful if Mail on Sunday had reminded readers that The Food Doctor is a trademark brand name and not a professional title as there is still some confusion about this. It’s a shame that we didn’t hear more from Catherine Collins or another Registered Dietitian who might have been able to provide fuller guidance on identifying troublesome foodstuffs through a detailed diary.[f]

Note to Mail on Sunday – please ask a Registered Dietitian to write pieces such as this. RD’s recommendations are evidence-based and practical.

There is unlikely to be a single cause for bloating and distension, which probably have different, but overlapping, pathophysiological mechanisms. Relieving constipation might help distension, but the treatment of bloating may need more complex approaches involving sensory modulation.

There is no body of clinical literature that would readily generalise to support Marber’s exclusion diet for the alleviation of bloating and gas.

[b] A number of studies suggest that there are qualitiative differences in the colonic flora of people with IBS; a consistent finding is a comparatively lower population of bifidobacteria. However, some researchers have failed to reproduce these differences in their own evaluations and question the methods used by other groups.[d]

[c] For those who favour the concept of the gut as a second brain and believe that their gut talks to them, this is not an elaborate word game involving verbs. In very broadbrush terms, dietary fats may need to be emulsified before they can be absorbed: although some of this is achieved through mechanistic churning, the gut relies upon the action of conjugated bile salts to achieve this emulsification (conjugated bile salts have a more favourable pKa than deconjugated bile salts at normal levels of gut pH).
There are circumstances, such as small intestine bacterial overgrowth (SIBO) when these bacteria will deconjugate the bile salts, thus reducing fat digestion and absorption. However, this tends to be readily apparent for a number of reaons that the more squeamish would thank me not to elaborate but involve pale colour, floating and volume with perhaps some malodorousness. Those who are interested might read more about steatorrhoea and varieties of diarrhoea and the wonders of secondary fat maldigestion/malabsorption.
Nonetheless, appropriate deconjugation of bile acids may be important in the ecology of the gut for several reasons:

they inhibit bacteria more than conjugated bile acids

they may augment the activities of intestinal lactobacilli in countering various intestinal pathogens thus maintaining an appropriate balance in gut ecology

However, a substantial distortion might result in clinically significant disruptions in water and electrolyte transport in the colon, affecting colon motility and/or sensation.

[d] These are changes that are so substantial that they are termed SIBO. However, Quigley[2] gives a good overview of the mixed fortunes of using antibiotics to treat hypothecated overgrowth of bacteria.

These results, in the opinion of this author, are far less impressive than one was led to expect from the initial studies by these same authors 27,28 and also cast further doubt on the importance of bacterial overgrowth in IBS. Finally, one must remain reluctant, pending long-term studies, to recommend a prolonged course of antibiotic therapy to any population regardless of the safety profile of a given antibiotic.
Given their safety profile, probiotics, if effective, would at first sight appear to be a more attractive as potential manipulators of the gut flora in IBS. Are probiotics effective in IBS?…[T]here has been some, but by no means consistent, evidence of symptom improvement.45–58 In a recent review Hamilton-Miller, while drawing attention to the shortcomings of prior trials in terms of study design, concluded that there was, overall, sufficient evidence of efficacy to warrant further evaluation.59

Always an honour to have you drop by, Professor UK Dietitian. Thank you for the kind sentiment but we know our limitations and doubt that the average Mail reader is quite as interested in the actual state of the evidence as we are – which should not preclude them receiving accurate advice, from an appropriately-credentialled person – such as an RD. They really must stop mucking about with people who are good at self-promotion (outstanding in fact) but are happy to advance half-baked or wholly un-evidenced advice.

Disclaimer

At the risk of sounding like Arthur Weasley, information on this blog is not intended as a substitute for advice from a qualified medical practitioner. If you have health concerns, see a Dr or dietician (a blog is not the place to diagnose a health problem).